JPS6069833A - Manufacture of magnetographic carrier having lined layer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention comprises a non-magnetic flexible carrier sheet and a magnetic layer formed on one surface thereof of an organic binder and magnetic material powder. A dispersion prepared by mixing a non-magnetizable conductive and non-conductive solid material powder and conventional additives with a solution of a polymeric binder in an organic solvent is applied to a knife coating device. Accordingly, the above (''1) on the opposite side to the magnetic layer is
The present invention relates to a method for producing a magnetic recording carrier having a thin backing layer applied and dried on the surface of a body sheet.

(Prior Art) Containing non-conductive and/or conductive material that cannot be magnetized1
Flexible magnetic record carriers provided with backing layers are known.

US Pat. No. 3,293,066 states that the electrostatic charging of magnetic tapes that can occur at tape speeds exceeding 5 m/sec in equipment used for digital recording requires the provision of a conductive backing layer. It is also described that this can be avoided by making the back side of the tape abrasion resistant.
It is also known from US Pat. No. 7,661 and US Pat. No. 4,3503, T'J to improve the winding performance of the tape by providing a backing layer with a roughened surface. It is also known to provide magnetic cards with eleven such back layers. West German A=', 2500546~υ! jlJ at il
It is also known that such backing layers are used for video cameras and the like.

In this last case, the backing layer exhibits a particularly positive BuA effect on defect behavior during regeneration operations. For the tape, please refer to the back J.
The J layer is 0.2 to 5.0/1 m, especially 0.4 to 1.
Make it 2/1m thick. To form such a thin layer, a dispersion prepared by mixing non-magnetizable, conductive and non-conductive material powders with one or more solvents and binders is used. The liquid needs to be very dilute, i.e. the filter dispersion used to form the backing layer contains a relatively thick 1↑1 solvent content and therefore has a low viscosity. There is a disadvantage that the shrinkage rate, that is, the ratio of the coating thickness to the dry thickness of the layer increases, and the viscosity decreases rapidly, making it impossible to control the application of the dispersion onto the carrier sheet. The liquid becomes extremely unstable due to excessive solvent content 2.

Binders known per se, such as polyacrylates, polyamides, cellulose nidrades, polyesters, polyurethanes, phenoxy Mtl fats, copolymers of vinyl chloride and acrylonitrile, vinyl chloride, vinyl heptatate and copolymers of vinyl alcohol. Most of them are hard and brittle.

However, mechanical stresses in the backing layer require flexibility. For this reason, relatively brittle polymers such as phenoxy resins, vinyl chloride, vinyl acecou I copolymers, polycarbonate, etc. are often combined with polyurethane elastomers. However, such amalgamating agents cannot be conveniently diluted.

(Problem to be solved) Therefore, the problem to be solved by the present invention is to
A dispersion of dual electrically conductive and non-conductive powder 451 mixed in a binder solution is applied onto a carrier sheet, preferably by a knife coating device, without causing any side defects. It is an object of the present invention to provide a method for manufacturing a magnetic record carrier having a uniform backing TJ layer of 7'A layer thickness. Furthermore, this back IJ layer must be uniform despite its thin thickness and be extremely mechanically stable. This extremely thin layer (geometrically 1゛t1″l:)−1
'' [1+i for claims brought by new recording technology.
;: It must be something interesting.

(-1, means of determining the problem 9 Shikuruni-1-Polymer whose viscosity is 60% viscosity of dispersion 11) The organic compound is added to the polymer binder content: 11 At 47X- of 3 to 30 weight [i;%], by adding to the dispersion, the thickness of
It has now been found that a thin non-magnetic conductive to non-conductive backing layer can be conveniently formed using a knife coating device, thereby solving the above problem.

Suitable high molecular weight organic compounds are nitrocellulose with a K value of 75 or more, especially 90 or more, preferably 100 to 200, and those having a K value of 75 or more when reacted with diisocyanates or polyisocyanates. 90 or more, preferably from 100 to 200, such as cellulose acetobutylade, cellulose acefute, and cellulose globionate. When reacting with diisocyanates and/or polyisocyanates,
Molecular expansion occurs due to crosslinking in the OH groups of cellulose molecules.

The high molecular weight organic compounds to be added to the dispersion according to the process according to the invention are advantageously added in the amounts mentioned above, especially in an amount of 5 to 20%, based on the amount of polymeric binder It in the dispersion. .

The composition and preparation of the polymeric binder dispersion of the magnetic lateral slopes is by methods known per se and customary.

The binders are likewise selected from among those known per se for the production of magnetic record carriers. Copolyamide-17]ζ1 nohinyl mediral, polyurethane elastomer, 7I; IJ isocyanate and polymeric polyhydroxyl compound or 6
Copolymers of 0% or more of vinyl chloride with polyvinyl chloride, such as KF 11 monomers or comonomers of multiple types, such as vinyl/l/esters of monocarboxylic acids having 2 to 9 carbon atoms; is an ester of an aliphatic alcohol having 1 to 9 carbon atoms and an unsaturated carboxylic acid having 3 to 5 carbon atoms, such as acrylic acid, methacrylic acid or maleic acid. Vinyl chloride co-■ [combination, or eyes, type 1 H or &-. These carboxylic acid white books of IW number ΦJi'i can be used as a copolymer of a comonomer and 1f vinyl chloride, or as a partial polymer of a copolymer of vinyl chloride and vinyl ester. or vinyl chloride and a hydroxyl group-containing monomer, such as evalyl alcohol, 4-human-■oxybutyl or 2
- Hydroxyl group-containing vinyl chloride covalent polymers that can be prepared by direct polymerization with monomers such as acrylate (or methacrylate). Also suitable as a binder are mixtures of one or more polyurethane elastomers with polyvinyl methylal, phenoxy resins and vinyl chloride copolymers of a double composition. In particular, West German Patent Publication <1; Publication 1106
No. 955 and No. 27536971, Pue and West Germany'
The hydrolysis of polyurethane elastomers with a K value (1% in DMF) up to 75 and the exclusive reaction of vinyl ester polymers with vinyl alcohol polymers and formaldehyde, as described in I'4J Publication No. 2442762. Polyvinyl methylal, produced by Polyvinylmethylal, is a particularly advantageous binder. This v5+-a, at least 6
It is preferred that the polyvinyl methylal has a vinyl alcohol group content of 5% by weight, especially at least 80 wt. There are some that contain 80 to 88% by weight of vinyl methylal groups, have a specific gravity of about 1.2, and a K value (% in DMF) of 60±5. The mixture of binders is highly 9ji6.

As solvents for the preparation and processing of the above polymers, ethers of tetrahydrofuran and dioxane, ketones such as methyl ethyl ketone sanone are used. As is well known, there are other extremes such as polytamine, dimethylformamide lolidone, dimethyl sulfoxide, and ethylene glycol acetate. /14 solvent is also riJ soluble. -1 A series of solvents such as doluol, aromats such as quidylol and ethyl acetate.
It is also possible to mix it with an ester such as butyl acetate.

For dispersion preparation, the general formula n'-coo++
(In the formula, R' represents 10 to 22 carbon atoms, and 0 represents a linear to 4 branched alkyl group to an alkylene group.) 1st Nomu 3
i: Jj3:' metal salt with the above-mentioned carboxylic acid,
It is preferable to use a dispersion aid containing lecithin σ)αII. In this case, the amount of Y added is 2 to 3 TJ to the pigment.
(The amount is expressed as %.

As a lubricant for adjusting the friction properties, conventional lubricants such as fatty acid esters of mono- and dicarboxylic acids, fatty acid amides, and silicone oils are used. Refining amount is about 1 weight u1 of binder
．． % is appropriate.

Zinc oxide, titanium dioxide, α-Fe20 are used as additives to adjust the roughness of the backing layer and to strengthen it.
3. Calcium carbonate, barium sulfate,
Add corundum, chromium trioxide, silicates, etc.

Depending on the intended use, for example in the audio or video field, organically treated silicic acid with an average precipitated particle size of about 4 μm or a suitable silicic acid with an average secondary particle size of about 3 μm can be added to the cubic lattice ironite. It is also preferred to use it with acid salts. The ratio of bonding j1 to face 4"l of the backing layer is preferably between 1 1 and 4.1, in particular between 1.5: ] and 2.5: ]. Soot, for example, has a specific surface area of about 200 to'/f!, oil number 1.8
5 m+! 7 100 it', carbon content approximately 98% by weight
This is oil-fired furnace soot. Even larger specific surface area 1000
n? / f or smaller specific surface area 100 7712
/9 soot or a mixture thereof may also be used.

If a binder or binder mixture is used, an active polyisocyanate may be added before or during application of the backing layer dispersion to the 411 sheet, and optionally tempering of the backing layer may be carried out. This may be advantageous in terms of durability. A polyisocyanate, in particular a di- or triisocyanate diphenylmethane and 1 mol of a triol, such as glycerin or 1,111-trimethylolpropane, in particular 3 mol of toluylene diisocyanate and 1 mol of 1.1. The reaction product from 1-trimethylolpropane is applied to the 41-j body sheet-1 to provide hardness to the prepared magnetic layer dispersion and to improve the mechanical properties of the magnetic VL layer produced according to the invention. can be improved by reducing thermoplasticity. For this purpose, the addition of polyisocyanate (hi, total binder gT) is generally 1
It is 0 to 40% by weight. The cross-linking reaction ('i) is accelerated by the addition of a catalyst (e.g. triethylamine, triethylenediamine, It+-methyl-pyridine, N-
Tertiary amines such as methylmorpholine, potassium acetate,
Metal salts such as zinc stearate, organometallic compounds such as dibutyltin dilaurate are added.

Preferred compositions are from 20 to 35% by weight, in particular from 20 to 3% by weight.
0% by weight of conductive soot, 5 to 15% by weight, especially 8 to 12% by weight of pyrogenic or precipitated silicic acid, 2 to 8% by weight
, especially 3 to 6% by weight of cubic zinc ferrite, 0
．． 5 to 5% by weight, especially 1 to 3% by weight of carbon atoms 1
0 to 22 long-chain carboxylic acids, and 30 to 50% by weight, especially 35 to 45% by weight of a polymeric binder, and optionally 10 to 40% by weight, especially 20 to 40% by weight. % of polyisocyanate resin, forming a backing layer with a thickness of 0.2 to 5.0 μm.

The dispersion is prepared in a customary manner using a ball mill, vertical or horizontal stirrer. Preferably, the backing layer application is carried out with a coated liner. Pass through a heating chamber to evaporate the solvent and dry and cure the backing layer. In this case, the magnetic layer dispersion and the backing layer dispersion may be treated simultaneously, or they may be treated sequentially, that is, first the magnetic layer is then treated at .degree. C. and the backing layer, or vice versa. If necessary, the layered sheet is heated in conventional equipment, optionally to 500 to 100"C, or 60 to 80"C;
It is also pressurized and polished and compressed by passing it between heated polishing rolls. The j′;1 height of the back 41 layer is less than 571 m, especially 0.4
The thickness should be between 1.4 μm and 1.4 μm.

According to the present invention, a thin 1/irn or less thick
Moreover, it is possible to form a uniform back layer with an even thickness.
, s, in particular from 20 to 50 mPa, e, and in which the ratio jj of carbohydrate to solvent is at least 1:25 has proven particularly suitable. It is highly preferred that the nail ratio of solid separation solvent is at most 1:30 to I
:36, but up to the upper limit of 1:40, 1;'1
I can't stand it.

Formation of the backing layer using a knife coating device on a flexible carrier sheet by the method [Non-explosion jJI] is carried out in such a manner that its IIM silk ratio is 1, and the ratio of the coating thickness to the surface J'J layer thickness after drying is 10. In the case of I, especially in the case of 15 to 35, there is 4"1
] There is.

The magnetic recording carrier produced in accordance with the invention and having a backing layer of 11 layers has an average thickness of about 0.00 mm compared to those of the prior art, especially when the backing layer dispersion is applied by conventional coating methods.
It is excellent in that it is possible to form a layer with an extremely thin thickness of about 7 μm, thereby making it possible to minimize defects in the produced videotape, and to partially equalize defects in the sheet.

The following examples illustrate the invention in more detail in comparison with the prior art. All parts and percentages used herein refer to parts by weight and percent by weight unless otherwise specified. (%.

Example ↑ 500 steel balls with a grain size of 4 to 6 am and a specific surface area of 200 rn' in a 6000 capacity ball mill at the bottom.
/2 conductive soot 90 parts, average condensation diameter 4 μm0) 45 parts organically treated silicic acid, 15 parts gravity lattice zinc ironite, 3 parts stearic acid, 420 parts tetrahydrofuran, adipine,
Butanediol-1,4 and 4,4'-diisocyana~
Linear polyester made from todiferolmethane
13% tetrahydrofuran solution of urethane resin 2xc+
234.4 parts of an 8% solution of nitrocellulose with a K value of 110 in teI-rahydrofuran.

The ball mill is closed and the charge is blended and milled for 4 days. Take a sample of the dispersion from the mill to confirm the rheological data. It exhibited a viscosity of 374 mPa and a s % flow index of 40.5 Pa. Ball-milled the above-mentioned linear polyester-urethane resin σ 3% dissolved in tetrahydrofuran, 4% phenoxy resin σ 20% made from bisphenol A and chlorohydrin containing 6% hydroxyl groups.
171.2 parts of a tetrahydrofuran solution, 30 parts of a 0.1% silicone oil solution in tetrahydrofuran, and further 627 parts of tetrahydrofuran were added and mixed for 24 hours.

The dispersion was removed from the mill and the processing viscosity was adjusted to 22 mPa. Adjusted to s. This viscosity serves as a reference standard in all the following Examples and Comparative Experiments. Dispersion o. Add to the above 95.8 parts of a 50% solution of isocyanate resin in ethyl acetate prepared from 600 parts of +000 parts of tetrahydrofuran and 1 mole of trimethylol proppant to crosslink and cure the coated layer. and stir for 15 minutes. After filtration with filter paper, this solution (1) is applied by a coating device onto a sheet of polyethylene terephthalate with a thickness of 15 μm and dried in the dry zone of a layering device. The layer thickness was 0.9 μm.

Therefore, the shrinkage factor is 16.6. The backing layer was uniform and no layer pattern was observed. A magnetic layer is formed in a conventional manner on the back side of the 1g sheet, opposite to the J layer. Calendar Process 3]j After L, cut into A inch wide tape. This tape was tested continuously on a 'VHS-style recorder, with continuous R I'ol longer than 15 μsec per minute.
I confirmed the level down value of 20 dB.

The results are shown in the table at the end.

Example 2 Similar to Example 1, but instead of an 8% solution of nitrocellulose with a value of 110, a 5% solution of nitrocellulose with a value of 130. A dispersion was prepared using This dispersion has a viscosity of 713 mPa. s, 70-index 45.
9 Pa. This prepared dispersion was processed to a viscosity of 20 m.
Pa. On August 8th, 191 points were adjusted. Therefore, the dispersion] 000
750 parts of tetrahydrofuran and 90.8 parts of the 50% incyanato resin solution of Example 1 were added. This dispersion for the back J'1 layer was applied to the carrier sheet 1- using a coating device. For a coating thickness of 15 μm, the layer thickness after drying was 0.6 μm. The shrinkage factor is 25. The formed backing layer was extremely uniform. Example 1
A magnetic layer was applied in the same manner as above, post-treated and subjected to 7 tests. The measurement results are shown in the table.

Example 3 A dispersion liquid was prepared in the same manner as in Example 1, but A, 1 [with a slightly different composition, 13 of the linear polyester urethane resin]
%Solubility a96. z part, 122.6 parts of a 13% solution of polyvinyl methylal resin with a K value of 70, K value] 30-2 I・rt
375 parts of a 5% solution of cellulose and 428.4 parts of tetrahydrofuran were charged and mixed and ground for 411 hours.

Viscosity 729 mPa. , s , flow index 3!
L9 Pa.

showed that. Then 13% of polyester urethane resin
Bath liquid 8G! 1.2 parts 20% solution of phenoxy resin 15
G. 9 parts of silicone oil, 30 parts of a 0.1% tetrahydrofuran solution of silicone oil, and 608.3 parts of tetrahydrofuran were further added, and the mixture was stirred for 24 hours. The processing viscosity of the obtained backing layer dispersion was 22.5 mPa. Adjusted to s. 1000 parts of the dispersion is diluted with 1000 parts of tetrahydrofuran, and 89.6 parts of the above-mentioned incyanate solution is added. A backing layer was formed to a thickness of 2Q11m using a coating device, and the layer thickness after drying was 0.7 μm. The shrinkage coefficient is 28.
It becomes 5. This backing layer was extremely uniform. Example 1
A magnetic layer was applied and tested in the same manner as described above. The results are shown in the table.

Comparative Experimental Example 1 According to Example J, a binder known from West German Patent Specification No. 2500546, adipic acid, butanediol-1
．． A dispersion was prepared from a linear polyester urethane made from 4- and 4,4'-diisocyanatodiphenylmethane, a phenoxy resin made from bisphenol A and epichlorohydrin, and the additives and pigments shown in Example 1. .

Further, 363 parts of a 3% solution of linear polyester urethane and 360 parts of tetrahydrofuran were added, and the mixture was mixed and ground for 411 minutes. The viscosity of the CI dispersion is 105.4 m
Pa -8% Flow index is 5],,4 Pa
, there was. Next, ``Linear polyester urethane 1''
187.7 parts of a 3% solution of C, 87.7 parts of a 20% solution of phenoxy resin, 87.7 parts of a 0.1% solution of silicone oil in tetrahydrofuran? (1,30 parts, TeI Lahydrofuran 650
1 part was added, and the mixture was further mixed and ground for 2.1 hours. After dispersion treatment, this dispersion liquid was treated with a viscosity of 19 mPa, s K.
adjust. For this, 1000 parts of the dispersion are diluted with 500 parts of tetrahydrofuran and 103 parts of the incyanate resin solution of Example I are added. When this dispersion is layered onto a pressed sheet-1 using a coating device to give a layer thickness of 0711 m, the layer thickness after drying is 1.1/1 m, and the shrinkage coefficient in this case corresponds to 9. Due to the thin coating thickness,
Dirt builds up under the coating device, resulting in significant stratification and formation of a non-stratified film in places.

A magnetic layer was formed in the same manner as in the previous example (-1 was cut into tapes and used for testing. The results are shown in the table.

Experimental Example 2 in China 2 A magnetic recording carrier tape was prepared by applying a magnetic layer on a polyethylene tereflate sheet as described in Example 1, but without applying a backing layer, and was also subjected to the test. did.

The results are shown in the table below.

Surface Shrinkage Coefficient Defect Rate Example 1 16 ] 0 258 3 28.5 5 Comparative Experiment Example 1920 〃250 Patent Applicant Basfachchengesellschaft Representative Patent Attorney 1) Osamu Yo Sakazuki Continued from page 1 0 intervenor Werner , Grau@Inventor Unilner, Partz Inventor Reinhold, Baul, Federal Republic of Germany, 6712, Pobenheim-Loxheim, Toutzbreicher, 5 Federal Republic of Germany, 6703. Limburger Hof, Klopsburg Strasse, 44 Federal Republic of Germany, 7600, Offenburg, Strassburger, Strasse, 15 A.

Claims (1)

[Claims] 0) Comprising a non-magnetic flexible carrier sheet and a magnetic layer formed on one surface of the carrier sheet consisting of an organic binder and a magnetic material powder, the organic binder has an organic binder and a polymer bond in a solvent. A dispersion prepared by mixing conductive and non-conductive solid material powders and conventional additives into a solution in which the agent is dissolved is coated with a knife coater on the side opposite to the magnetic layer. Above 11.!
A thin backing formed on the outer sheet surface and drying step 1.
In the method for manufacturing a magnetic recording carrier having a layer "U."
Add a high molecular weight compound that makes 1% of the solid and viscous properties of the dispersion described above to 3% to the polymer binder portion.
to: 30 Ichio 9% σ Kawa Ii;, the method of adding it to the dispersion is a special feature 0 (2) '+': i The magnetic recording carrier described in the claims (]) A method for producing nitrocellulose, characterized in that the polymer compound is nitrocellulose having a value of 75 or more. (3) In the method for producing a magnetic recording carrier according to claim (1), the above-mentioned high molecular weight organic compound is obtained by reacting a cellulose reaction product with a diisocyanate or a polyisocyanate, A method characterized in that it has a value of at least .